U.S. patent application number 12/144812 was filed with the patent office on 2009-01-29 for wind turbine blade with cambering flaps.
This patent application is currently assigned to GAMESA INNOVATION & TECHNOLOGY, S.L.. Invention is credited to Michael Friedrich, Christian Meldgaard, ANDERS REBSDORF.
Application Number | 20090028704 12/144812 |
Document ID | / |
Family ID | 39679299 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090028704 |
Kind Code |
A1 |
REBSDORF; ANDERS ; et
al. |
January 29, 2009 |
WIND TURBINE BLADE WITH CAMBERING FLAPS
Abstract
A wind turbine having at least a blade comprising a first
component (11) having an aerodynamic profile with a leading edge
(5), a trailing edge (7) and suction and pressure sides between the
leading edge (5) and the trailing edge (7) and a second component
(13) attached to the trailing edge (7) and/or to the leading edge
(5) of the first component (11) in at least a part of the blade, in
which the second component (13) comprises an upwards and/or
downwards deflectable flap (15) that allows changing the flow over
the blade and in which the means for deflecting the flap (15)
comprise a stiff plate (31) inserted between the first component
(11) and the flap (15) and stiff plate actuating means (33,
43).
Inventors: |
REBSDORF; ANDERS;
(Silkeborg, DK) ; Friedrich; Michael; (Silkeborg,
DK) ; Meldgaard; Christian; (Silkeborg, DK) |
Correspondence
Address: |
LADAS & PARRY LLP
26 WEST 61ST STREET
NEW YORK
NY
10023
US
|
Assignee: |
GAMESA INNOVATION & TECHNOLOGY,
S.L.
|
Family ID: |
39679299 |
Appl. No.: |
12/144812 |
Filed: |
June 24, 2008 |
Current U.S.
Class: |
416/23 |
Current CPC
Class: |
F03D 1/0675 20130101;
F03D 7/0232 20130101; F05B 2280/2001 20130101; F05B 2270/605
20130101; F05B 2240/311 20130101; F05B 2270/404 20130101; F05B
2260/50 20130101; Y02E 10/72 20130101; F05B 2240/3052 20200801;
F05B 2270/331 20130101; F05B 2240/301 20130101; F03D 1/0641
20130101; F05B 2280/6003 20130101; F05B 2280/4003 20130101 |
Class at
Publication: |
416/23 |
International
Class: |
F03D 11/00 20060101
F03D011/00; F01D 5/14 20060101 F01D005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 23, 2007 |
ES |
P200702050 |
Claims
1. A wind turbine having at least a blade comprising a first
component (11) having an aerodynamic profile with a leading edge
(5), a trailing edge (7) and suction and pressure sides between the
leading edge (5) and the trailing edge (7) and a second component
(13) attached to the trailing edge (7) and/or to the leading edge
(5) of the first component (11) in at least a part of the blade,
characterized in that: the second component (13) comprises an
upwards and/or downwards deflectable flap (15) that allows changing
the flow over the blade; the means for deflecting the flap (15)
comprise a stiff plate (31) inserted between the first component
(11) and the flap (15) and stiff plate actuating means (33,
43).
2. A wind turbine according to claim 1, characterized in that the
stiff plate actuating means are vacuum operable inner chambers (33)
which are located in the first component (11) close to the stiff
plate (31).
3. A wind turbine according to claim 1, characterized in that the
stiff plate actuating means are pressure operable inner chambers
(43) which are located in the first component (11) close to the
stiff plate (31).
4. A wind turbine according to claim 1, characterized in that the
stiff plate actuating means are vacuum and pressure operable inner
chambers (33, 43) which are located in the first component (11)
close to the stiff plate (31).
5. A wind turbine according to claim 1, characterized in that the
wind turbine also comprises means for controlling said actuating
means (33, 43) depending on the wind situation and/or the loads on
the blade.
6. A wind turbine according to claims 1, characterized in that the
flap (15) is made in one piece of a flexible material.
7. A wind turbine according to claim 6, characterized in that the
flap (15) is made of rubber.
8. A wind turbine according to claim 6, characterized in that the
flap (15) is made of a pultruded fiber glass reinforced
composite.
9. A wind turbine according to claim 1, characterized in that the
width W of the flap (15) is comprised between 1-20% of the chord
length C of the blade in the center of the flap (15).
10. A wind turbine according to claim 9, characterized in that the
width W of the flap (15) is constant along the blade.
11. A wind turbine according to claim 9, characterized in that the
width W of the flap (15') is variable along the blade.
12. A wind turbine according to claim 1, characterized in that the
flap (15) is attached to the blade leading edge (5) and/or to the
blade trailing edge (7) in a section having a length lesser than
1/3 of the blade length L.
13. A wind turbine according to claim 1, characterized in that the
blade includes one or several second components (13) having each of
them an individual flap (15, 15') with individual stiff plate
actuating means (33, 43).
Description
FIELD OF THE INVENTION
[0001] The invention relates to a wind turbine having rotor blades
with cambering/deflectable flap s and in particular to rotor blades
with deflectable flaps for optimizing the blade loads.
BACKGROUND
[0002] Wind turbines are devices that convert mechanical energy to
electrical energy. A typical wind turbine includes a nacelle
mounted on a tower housing a drive train for transmitting the
rotation of a rotor to an electric generator.
[0003] The efficiency of a wind turbine depends on many factors.
One of them is the orientation of the rotor blades with respect to
the direction of the air stream, which is usually controlled by a
pitch system that allows adjusting the pitch angle of the rotor
blades for maintaining the rotor's speed at a constant value or
within a given range. Otherwise, specially at high wind speeds, the
load of the rotor will exceed the limits set by the wind turbine's
structural strength.
[0004] There are two basic methods for controlling the power of a
wind turbine changing the pitch angle of the rotor blades: the
"pitch" control method and the "stall" control method.
[0005] In the "pitch" control method the rotor blade's pitch angle
is changed to a smaller angle of attack in order to reduce power
capture and to a greater angle of attack to increase the power
capture. This method allows a sensitive and stable control of the
aerodynamic power capture and rotor speed.
[0006] In the "stall" control method the rotor blade's pitch angle
is changed to a greater angle of attack to the point where the flow
separates at the rotor blade's surface, thus limiting the
aerodynamic power capture.
[0007] The pitch regulated wind turbines can also use the pitch
system to reduce the dynamic loads, either by cyclic pitch or by
individual blade pitch. However, for large wind turbine blades it
can be difficult to control the blade loading as the blade loading
can vary over the blade length. As the rotor size is increasing,
the pitching of the blades not necessarily provides an optimized
loading along the whole blade because nor only wind shear, yaw
errors and gust will affect the flow on the blade, but different
gusts can hit the blade simultaneously or complex wind shear
profiles with negative wind shear can occur.
[0008] In addition to the use of the pitch system there are known
in the prior art some proposals in the prior art for optimizing the
blade loads.
[0009] One known proposal is the use of small control surfaces such
as Gurney flaps attached to the trailing edge for optimizing the
blade loads. One disadvantage of Gurney flaps is the increase in
aerodynamic noise from the free ends of the Gurney flaps and from
the gaps in the blade where the Gurney flap is positioned.
[0010] Another known proposals are addressed to control the
aerodynamic forces along the rotor blades by a continuous variation
of the airfoil geometry in the leading edge region and trailing
edge region along part of or along the whole blade span.
[0011] One of these proposals, disclosed in WO 2004/088130, relates
to a design concept by which the power, loads and/or stability of a
wind turbine may be controlled by a fast variation of the geometry
of the blades using active geometry control (e.g. smart materials
or by embedded mechanical actuators), or using passive geometry
control (e.g. changes arising from loading and/or deformation of
the blade) or by a combination of the two methods. In one preferred
embodiment piezoelectric plates are to built in the trailing edge
over part of the blade for modifying its geometry in order to
reduce the blade loads. One disadvantage of the piezoelectric
plates are the electrical cables that are necessary to bring power
to them. These cables are woundable to electrical lightning and can
easily be damaged in case of a lightning strike.
[0012] Another proposal, disclosed in U.S. Pat. No. 6,769,873,
relates to a dynamically reconfigurable wind turbine blade assembly
including a plurality of reconfigurable blades mounted on a hub, an
actuator fixed to each of the blades and adapted to effect the
reconfiguration thereof, and an actuator power regulator for
regulating electrical power supplied to the actuators.
[0013] None of these proposals produces fully satisfactory results,
therefore a continuing need exists for wind turbines having rotor
blades with means for reducing the blade loads.
SUMMARY OF THE INVENTION
[0014] An object of the invention is to provide a wind turbine
that, in addition to a pitch system, has special means for
achieving an accurate control of the blade loads.
[0015] Another object of the invention is to provide a wind turbine
having means for controlling the changes in the flow and hence
optimizing the whole rotor performance and minimizing the pitch
activity of the blades.
[0016] These and other objects of the present invention are met by
providing a wind turbine with rotor blades comprising a first
component having an aerodynamic profile with a leading edge, a
trailing edge and suction and pressure sides between the leading
edge and the trailing edge and a second component, attached to the
trailing edge and/or to the leading edge of the first component in
at least a part of the blade, which comprises an upwards and/or
downwards deflectable flap that allows changing the flow over the
blade, and means for deflecting the flap including a stiff plate
inserted between the first component and the flap and stiff plate
actuating means.
[0017] In a preferred embodiment, the stiff plate actuating means
are vacuum and/or pressure operable chambers/tubes located in the
first component. The flap deflection is controlled by load
measurements on the blade, velocity or pressure measurements of the
air on the blade or lidar measurements of the flow in front of the
blade. With the load feed back and the appropriate control
algorithm the flap can be used to control the blade loading more
accurate than in the prior art. Hereby "active" controlled
deflectable flaps are achieved.
[0018] Other features and advantages of the present invention will
be understood from the following detailed description in relation
with the enclosed drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a schematic cross sectional view of a wind turbine
blade according to the present invention showing the second
component attached to the trailing edge of the first component.
[0020] FIG. 2 is a schematic cross sectional partial view of a wind
turbine blade according to a first embodiment of the present
invention showing the second component attached to the trailing
edge of the first component.
[0021] FIG. 3 is a schematic cross sectional partial view of a wind
turbine blade according to a second embodiment of the present
invention showing the second component attached to the trailing
edge of the first component.
[0022] FIG. 4 is a schematic cross sectional partial view of a wind
turbine blade according to a third embodiment of the present
invention showing the second component attached to the trailing
edge of the first component.
[0023] FIG. 5 is a schematic sectional view of a wind turbine blade
incorporating a deflectable flap according to the present
invention.
[0024] FIG. 6 is a schematic sectional view of a wind turbine blade
incorporating two deflectable flaps according to the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] FIG. 1 shows the second component 13 attached to the first
component 11 of a wind turbine blade according to the present
invention.
[0026] The first component 11 has a typical aerodynamic profile
with a leading edge 5, a trailing edge 7 and suction and pressure
sides between the leading edge 5 and the trailing edge 7.
[0027] The following detailed description will refer to embodiments
of the invention in which the second component 13 is attached to
the trailing edge 7 of the first component 11. The invention also
comprises embodiments in which the second component 13 is similarly
attached to the leading edge 5 of the first component 11.
[0028] The second component 13 includes a deflectable flap 15 by
means of displacements of a stiff plate 31 inserted between the
first component 11 and the flap 15 which can be actuated in
different manners as it will be now explained.
[0029] A first embodiment of the present invention is shown in FIG.
2. The second component 13 is a deflectable flap 15 by means of a
stiff plate 31 inserted between the first component 11 and the flap
15, which is actuated by a vacuum operable inner chamber 33 located
at the first component 11.
[0030] Within this invention the term "chamber" shall be understood
in a broad sense as a body of a variable volume under pressure or
vacuum for an upwards or downwards displacement of the side of the
stiff plate 31 placed inside the first component 11 of the
blade.
[0031] A second embodiment of the present invention is shown in
FIG. 3. The second component 13 is a deflectable flap 15 by means
of a stiff plate 31 inserted between the first component 11 and the
flap 15, which is actuated by a pressure operable inner chamber 43
located at the first component 11.
[0032] A third embodiment of the present invention is shown in FIG.
4. The second component 13 is a deflectable flap 15 by means of a
stiff plate 31 inserted between the first component 11 and the flap
15, which is actuated by a vacuum operable inner chamber 33 and a
pressure operable chamber 43 located at the first component 11.
[0033] Pressure/vacuum applied with a fluid or gas medium in above
mentioned chambers 33, 43 is scaled to give a defined force over
the stiff plate 31 resulting in a change of the relative position
of the flap 15 with respect to the first component 11.
[0034] The wind turbine also comprises computer means for
controlling the actuating means 33, 43 that deflect the flap 15 in
a full active load control mode, taking into account load
measurements on the blade and relevant airflow parameters provided
by relevant sensors or in a semi active load control mode taking
into account the overall turbine conditions (without specific
sensor information).
[0035] The flap 15 is made in one piece of a flexible material such
as rubber and it is attached to the first component 11 with means
allowing its deflection as explained above. It can also be made as
a pultruded profile eg. in glass fiber reinforced composite
material.
[0036] The blade may include one individual flap 15 as shown in
FIG. 5 or several flaps 15, 15' as shown in FIG. 6. In the latter
case each flap 15, 15' has its own actuating means.
[0037] In a preferred embodiment, the width W of the flap or flaps
15, 15' is comprised between 1-20% of the chord length C in the
center of the flap.
[0038] The width W of the flap or flaps 15, 15' may be constant or
variable. In the first case the width will be usually smaller close
to the tip region and larger towards the root section of the blade.
In the latter case, the width W of the flap 15', as shown in FIG. 6
will decrease towards the tip of the blade.
[0039] In another preferred embodiment, the flap or flaps 15, 15'
are attached to the blade leading edge 5 and/or to the blade
trailing edge 7 in a section having a length lesser than 1/3 of the
blade length L.
[0040] Although the present invention has been fully described in
connection with preferred embodiments, it is evident that
modifications may be introduced within the scope thereof, not
considering this as limited by these embodiments, but by the
contents of the following claims.
* * * * *